The oxidation-reduction chemistry of manganese (II, III, IV) complexes is to be investigated by electrochemical, spectroscopic, and stopped-flow methods in aqueous and in aprotic solvents. The goal of the research is to discover manganese complexes and solution conditions which result in oxidation-reduction chemistry that mimics that of mitochondrial superoxide dismutase (SOD) and of the water-oxidizing species associated with photosystem II in green-plant photosynthesis. The ligands proposed for study are gluconate ion, triethanolamine, pyrophosphate ion, bipyridyl, and 8-quinolinol. Determination of the oxidation-reduction thermodynamics, reaction kinetics, and solution structures for the various manganese complex-solvent systems will be the means of characterization. Studies of the reaction chemistry and the chemistry of the reaction products for the various manganese complexes in combination with O2, O2-, and H2O2 are a major part of the project. Manganese systems analogous to the Haber-Weiss Fe(II)-H2O2 reaction for the formation of hydroxyl radicals are to be sought and characterized in terms of kinetics and mechanisms.